Ion implantation systems are used to impart impurities, known as dopant elements, into semiconductor substrates or wafers, commonly referred to as workpieces. In such systems, an ion source ionizes a desired dopant element, and the ionized impurity is extracted from the ion source as a beam of ions. The ion beam is directed (e.g., swept) across respective workpieces to implant ionized dopants within the workpieces. The dopant ions alter the composition of the workpieces causing them to possess desired electrical characteristics, such as may be useful for fashioning particular semiconductor devices, such as transistors, upon the substrates.
The continuing trend toward smaller electronic devices has presented an incentive to “pack” a greater number of smaller, more powerful and more energy efficient semiconductor devices onto individual wafers. Moreover, semiconductor devices are being fabrication upon larger workpieces to increase product yield. For example, wafers having a diameter of 300 mm or more are being utilized so that more devices can be produced on a single wafer. This necessitates careful monitoring and control over semiconductor fabrication processes, including ion implantation.
However, operation of an ion implanter or other ion beam equipment (e.g., linear accelerators) may result in the production of contaminant particles that in some cases may adhere to the wafers. The contaminant particles, for example, may be less than 1 μm in size. Particles that adhere to wafers during implant are often measured by putting wafers in a particle detection tool employed before and after ion implantation. Detection tool operations take additional capitol investment, consume additional time and resources, and present a potential exposure to further wafer contamination.
Such wafers are expensive and, thus, make it very desirable to mitigate waste, such as having to scrap an entire wafer due to particle contamination detected after ion implantation, after time and resources have already been invested. Further, detection after ion implantation makes it difficult to trace the source and causes of particles and other contaminates in such processes requiring numerous steps. In addition, it is desirable to minimize the use of traditional detection tools that may also provide a source of contamination and consume more time and resources.